Dishwashers have become an integral part of everyday household use. Consumers place dishware and other utensils onto dishwasher racks inside dishwashers for cleaning. Dishwashers typically clean the dishware with wash systems that utilize spray arms and spray jets to propel water onto the dishware to remove food particles and otherwise clean the dishware.
Since it is desirable to fully clean (and sanitize) dishware contained within the tub, wash water is often heated. As such, some dishwashers include a heating element to heat the wash water, prior to circulation thereof and/or as the water is circulated to wash or rinse the dishware. The heating element may often be provided in the form of a tubular resistance heating element located near the bottom of the tub.
Such heating elements, however, present a number of deficiencies that are less than desirable. For example, a tubular resistance heating element is typically positioned within the tub near the sump (e.g., the bottom of the tub), which occupies valuable space that could otherwise be used for storage of dishware for cleaning. Another issue with such a heating element is general inefficiency in heating the wash water. For example, the heating element has a limited surface area that is exposed to the volume of water flowing, which makes proper heating of the water difficult. Thus, such heating elements have a high thermal mass and a large heat storage capacity. Such inefficiencies in heating the water further lead to slow response of the heater and unequal distribution of the heat. Moreover, the heating element is disposed generally within the dishwasher so as to heat the water prior to the circulation pump receiving the heated water and circulating it through the dishware. In such instances, the heated water may lose some thermal energy prior to being circulated.
To maximum space within the tub and provide efficient heating, circulation assemblies with an integrated heater, pump, and motor have been developed. These circulation assemblies may be positioned outside of the tub, thereby increasing storage capacity within the tub for dishware. However, integrating the heater with a circulation pump and motor creates a number of potentially hazardous conditions. Additionally, placing the integrated heater, pump, and motor directly below the dishwasher tub also creates potentially hazardous conditions.